Velocardiofacial syndrome (VCFS) is a common, autosomal dominant genetic disorder. Several of the most frequent abnormalities observed in patients with VCFS can be explained, at least in part, by perturbation of a gene, or genes, required for neural crest cell migration or differentiation. However, additional abnormalities observed in the 22q11 deleted patients are not as clearly associated with neural crest cell migration or differentiation. For example, a significant number of patients with 22q11.2 deletions have genitourinary abnormalities and the majority of patients exhibit mild to severe developmental delay. While haploinsufficiency for a single gene could explain the broad and highly variable phenotypes seen in these patients, it is also possible that this complex disorder is due to reduced expression of several genes. Work in the previous funding cycle led to a complete physical map of the critical region and the identification of multiple genes. While numerous genes have been isolated from this region, studies performed thus far have not provided strong evidence for any one gene being directly responsible for all of the features seen in DGS/VCFS. In this project we propose to characterize selected genes by expression and functional analysis to determine their role in the etiology of this disorder. This will help determine the effect of reduced levels of the proteins in the pathogenesis of the syndrome. We hypothesize that there may be sequences in the 22q11 deleted region that have a global effect on transcription. Thus, experiments are proposed to determine whether the rearrangements are disrupting regulatory elements that influence the expression of DGS/VCFS-related gene. Finally, we propose to screen a cohort of patients who do not have deletions of 22q11 for mutations in candidate genes from 22q11 and other chromosomal regions. These studies should make a significant contribution to our molecular understanding of DGS/VCFS.